Released: Exchange Server 2013 RTM Cumulative Update 2

@Rick, the storage requirements do not change. Here is a simplified example. An item in a mailbox may have 50 properties (in reality it has way more), and let's say in the past we only used the size of 40 of those properties to calculate the total size of the item towards a user's quota. The space on disk was already utilized within the database, we just didn't report the last 10 properties of space back to the user. In 2013 all 50 theoretical properties are calculated towards total item size and applied towards a user's quota. The space within the DB the mail item uses isn't drastically changing, it is simply more accurately calculated to reflect what the user is actually using.